"We will launch a signature campaign across the country to collect five crore signatures and put pressure on the Centre to ensure food security for all. Every family must get 35kg of grains at the rate Rs 2 per kg without making any kind of distinction between those belonging to the below or and above poverty line categories," CPM general secretary Prakash Karat said.

Terming the Delhi government's decision to give Rs 600 per month to a BPL family as "insufficient", Karat doubted as how much grain a poor family could afford to purchase from the open market.

"Money could be misutilised and spent on different items.All these steps taken by the UPA government suit the interests of the market and retail giants like Walmart," he added.

Former CPI general secretary A.B. Bardhan, who shared tha dais with Karat during the state-level convention of the CPM, CPI, RSP and the Forward Bloc, said: "The government should not distribute money as it can't fill up stomachs. We (people) don't want money, we want foodgrains."

Prime Minister Manmohan Singh had on November 26 announced the Centre's plan for direct cash transfer of subsidies from January 1, 2013 in 51 districts of the country. The scheme would be rolled out in the remaining part of the country by April 2013.

The Left parties held the convention in protest against the Centre's "unilateral" decision to allow FDI in multi-brand retail. Karat said following agriculture, around 20 crore people's survival depended on the retail sector that provided employment to four crore people.

Claiming that Walmart employed 225 people for its supermarket, he said if such a retail giant was allowed in India, it would employ 214 people and render 4,000 jobless as 1,300 retail shops would be closed down following the opening of one store of the retail giant. Karat also criticised the Centre's plea of putting a cap of minimum investment limit of Rs 500 crore for opening supermarket for the foreign firm. "This is too small an amount for a firm like Walmart, which has an annual income of Rs 20 lakh crore," the CPM general secretary said.

Bardhan said FDI in the retail sector would neither create employment nor it would be in the interests of the farmers or the buyers.

"Firms like Walmart, Tesco and Carrefour would benefit those belonging to the higher medium class. FDI in the retail segment would in the long run detrimental for all sections of society. With a 'Stop Walmart' slogan, we will compel the government to withdraw its decision through a massive people's movement across the country. We will also stage demonstration both within and outside Parliament," he added.